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Subject[PATCH 2/2] intel_pstate: Set core to min P state during core offline
Date
From: Dirk Brandewie <dirk.j.brandewie@intel.com>

Change to use ->exit_prepare() callback to do clean up during CPU
hotplug. The requested P state for an offline core will be used by the
hardware coordination function to select the package P state. If the
core is under load when it is offlined it will fix the package P state
floor to the requested P state of offline core.

Reported-by: Patrick Marlier <patrick.marlier@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
---
drivers/cpufreq/intel_pstate.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 2cd36b9..e9092fd 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -447,7 +447,7 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
if (limits.no_turbo)
val |= (u64)1 << 32;

- wrmsrl(MSR_IA32_PERF_CTL, val);
+ wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
}

static struct cpu_defaults core_params = {
@@ -773,16 +773,22 @@ static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
return 0;
}

-static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
+static int intel_pstate_cpu_stop(struct cpufreq_policy *policy)
{
- int cpu = policy->cpu;
+ int cpu_num = policy->cpu;
+ struct cpudata *cpu = all_cpu_data[cpu_num];
+
+ pr_info("intel_pstate CPU %d exiting\n", cpu_num);
+
+ del_timer(&all_cpu_data[cpu_num]->timer);
+ intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
+ kfree(all_cpu_data[cpu_num]);
+ all_cpu_data[cpu_num] = NULL;

- del_timer(&all_cpu_data[cpu]->timer);
- kfree(all_cpu_data[cpu]);
- all_cpu_data[cpu] = NULL;
return 0;
}

+
static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
{
struct cpudata *cpu;
@@ -818,7 +824,7 @@ static struct cpufreq_driver intel_pstate_driver = {
.setpolicy = intel_pstate_set_policy,
.get = intel_pstate_get,
.init = intel_pstate_cpu_init,
- .exit = intel_pstate_cpu_exit,
+ .stop = intel_pstate_cpu_stop,
.name = "intel_pstate",
};

--
1.8.3.1


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